The relationship between the emergency nurses' sleep quality and the sleep quality of their spouses: A cross‐sectional descriptive‐analytical study

Abstract Background and Aims Due to the heavy working shifts, emergency nurses may have to sleep at unusual times of the day, affecting their spouse's sleep. This study proposed to detect the relationship between the woman emergency nurse's sleep quality and the sleep quality of their spouses. Methods This cross‐sectional descriptive‐analytical study has lasted for 4 months since June 21, 2020. The study population was all women nurses working at a hospital emergency department. The data was collected by a demographic questionnaire and Pittsburgh sleep quality index (PSQI) for nurses and their spouses. The data were analyzed by descriptive and inferential statistics. Results The prevalence of sleep quality disorder among female emergency department nurses and their husbands was 82.7% and 80.6%, respectively. The mean sleep quality score of female nurses and their husbands was 8.46 ± 4.43 and 6.50 ± 2.52, respectively. A strong and positive correlation was found between the PSQI score of female nurses and their husbands (p < 0.001). The regression model showed that increasing the body mass index (BMI) of female emergency nurses can decrease their sleep quality. However, increasing the BMI of female emergency nurses' spouses and their work experience in the emergency department can improve their sleep quality. Conclusion The sleep quality of female emergency department nurses was directly correlated with their husbands' sleep quality. Therefore, the sleep quality of nurses working in the emergency departments and their spouses should be examined periodically.


| INTRODUCTION
Many nurses who work rotating shifts have irregular sleep patterns. 1 In studies performed by Zhi-hao Tu et al., Bazrafshan et al., and Xuexue Deng et al., nearly 60%, 56%, and 46% of nurses had low sleep quality, respectively. [2][3][4] The low sleep quality of nurses negatively affects their health and reduces their performance during patient care. [1][2][3][4][5] It can also cause stress, depression, fatigue, burnout, obesity, cardiovascular disorders, and mental disorders. [6][7][8][9] Nurses working in emergency departments have lower sleep quality due to constant contact with critical patients. Studies conducted by Dong et al., Suleiman et al., and Weaver et al. reported that the prevalence of sleep quality disorders in emergency nurses is 65.8%, 92.1%, and 73.3%, respectively. [10][11][12] Reduced sleep quality is tied to fatigue, sleep, cognitive disorders, mental disorders, increased likelihood of medical errors, and declined job satisfaction in emergency nurses. [12][13][14][15] Decreased sleep quality and its subsequent problems can also affect the married lives of nurses, including decreased sleep quality of their spouses.
Nurses tend to sleep both before and after night shifts, 16 which may influence the sleep of their spouses. Walters et al. 17 reported that synchronized sleep patterns of couples could promote their psychosocial health. Tracy et al. 18 also argued a direct association between couples' sleep quality. Lee et al. 19 showed a positive correlation between sleep duration and couples' sleep quality.
Besides, this study mentioned the wife's sleep duration as a predictor of a man's sleep duration. Heather et al. 20 also reported that synchronized sleep patterns of couples could reduce blood pressure and decrease CRP. Liu et al. 21 and Zhang et al. 22 showed that poor sleep quality could cause work-family conflict in nurses. In reality, the sleep pattern of nurses is different from their spouses, which may cause physical and/or mental problems and reduce their quality of life. 22 Considering that the sleep quality of emergency nurses is lower than their counterparts, it seems that their spouses also have lower sleep quality than the spouses of other nurses. The current study aimed to investigate the association between the women emergency nurse's sleep quality and the sleep quality of their spouses.

| Study design and participants
This cross-sectional descriptive-analytical study has lasted for 4 months since June 21, 2020. The study population was all female nurses working at a 25 Mazandaran university hospital emergency department and had the inclusion criteria.

| Inclusion criteria
The participant and his spouse are willing to participate in the research. They must have completed the informed consent form before starting the study. When completing the questionnaires, the female nurses should have at least 1 year of working experience in the hospital's emergency department. They should not have the habit of using any sleeping pills or drinks to sleep or stay awake. When completing the questionnaire, they should not have pain or other physical and mental problems. They must be married, their husbands must not be nurses, and they must not have any restrictions on sexual activity with their husbands. Also, they do not have any history of previously known sleep disorders.

| Exclusion criteria
Unwillingness to continue participating in the study and, failure to complete and send the questionnaire.

| Sample size
The sample size was estimated by using the PASS 11, version 11.0.8.
At first, a pilot study was performed on the 15 nurses with their husbands. Then according to the correlation coefficient between sleep scores of nurses with their husbands (R = 0.626, p = 0.01), a significance level (α) of 0.01, and power of 0.99 using the test for two correlation, a sample size of 93 nurses with their husbands (total 186 samples) was calculated. To prevent a dropout in the sample size, it was increased to 117 nurses with their husbands (total 223) subjects by a 20% dropout rate.

| Measures
The data collection tools were a demographic questionnaire for the nurse, a demographic questionnaire for the nurse's spouses, and Pittsburgh sleep quality index (PSQI). This questionnaire was completed after receiving informed consent. breakfast is usually bread, cheese, butter, eggs, milk, and tea. After eating breakfast, they would go to their private homes and sleep. Therefore, their diet before sleep was almost the same. The sleeping environment has also been their home.

| PSQI
The PSQI assesses the sleep quality and disturbance retrospectively over 1 month. This is a 19 item self-report scale that measures sleep quality, and the survey can be completed within 5 min. This questionnaire is scored on a 4-point Likert scale from 0 to 3 (0, not in the past month; 1, less than once per week; 2, once or twice per week; and 3, three or more times per week) the total score ranges from 0 to 21, with higher scores indicating poorer sleep quality. This questionnaire has seven subscales: Subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, sleeping medication use, and daytime dysfunction. 23 The Persian version of the PSQI-P was used in the present study. Cronbach's α coefficient for all subjects was 0.77. Sensitivity and specificity are high (94% and 72%, respectively) for a PSQI-P cutoff value of 5. 24

| Procedures
A questionnaire on demographic information and a sleep quality questionnaire was used to collect the data. Participating nurses were asked to give the questionnaires to their spouses. Written informed consent was obtained from all nurses and their spouses willing to participate in the study. Then, the researcher provided the participants with two stamped envelopes with a return address (but no sender's address) and asked them to put the envelope in the nearest mailbox after completion. No code or mark was placed on the questionnaires to observe the confidentiality of information. However, they were asked to write a common code on both questionnaires to facilitate the identification of questionnaires or put both questionnaires in one envelope. Also, those participants who were willing to know their sleep quality status were asked to write their names and contact numbers on the questionnaire.

| Statistical methods
All analyses were performed using SPSS-16 software (SPSS Inc.). The Kolmogorov−Smirnov test showed that the data distribution was normal. The obtained data were analyzed using descriptive statistics, including frequency, mean, and standard deviation. The Pearson's correlation test was used to demonstrate the relationship between

| RESULTS
Initially, 106 nurses working in the emergency department and their spouses accepted to participate in the study, and 8 (7.54%) of them were excluded due to various reasons such as the incompleteness of questionnaires (5 subjects) and unwillingness to continue the study (2 subjects   husbands' BMI variables and the duration of work in the emergency department, the nurses' sleep quality improved (Tables 4 and 5).

| Study limitations
We asked participants to complete the questionnaires without the assistance and advice of their spouses or others. However, some of them may not have followed our advice. Therefore, this study is limited in this regard. The funders have had no involvement in the study design; collection, analysis, and interpretation of data; writing of the report; and the decision to submit the report for publication.

CONFLICT OF INTEREST
The authors declare no conflict of interest.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available on request from the corresponding author. The authors confirm that the data supporting the findings of this study are available within the article. The lead author Mr. Seyed-Hossein Hashemi-Amrei has full access to all of the data in this study and takes complete responsibility for the integrity of the data and the accuracy of the data analysis.

ETHICS STATEMENT
The